cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A355433 Numbers k such that k is sqrt(k)-smooth and k+1 is sqrt(k+1)-smooth.

Original entry on oeis.org

8, 24, 48, 49, 63, 80, 120, 125, 168, 175, 195, 224, 242, 288, 324, 350, 351, 360, 363, 374, 384, 399, 440, 441, 455, 475, 494, 512, 528, 539, 560, 575, 594, 624, 675, 714, 728, 735, 759, 832, 840, 874, 896, 935, 960, 968, 1000, 1014, 1023, 1044, 1053, 1088, 1104
Offset: 1

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Author

Amiram Eldar, Jul 02 2022

Keywords

Comments

Numbers k such that k and k+1 are both in A048098.
This sequence is infinite: if p is an odd prime then p^2-1 is a term.

Examples

			8 is a term since 8 is sqrt(8)-smooth (2^2 <= 8) and 9 is sqrt(9)-smooth (3^2 <= 9).
		

Crossrefs

Subsequences: A084920 \ {3}, A060355, A348119.

Programs

  • Mathematica
    smQ[n_] := FactorInteger[n][[-1, 1]]^2 <= n; Select[Range[1000], smQ[#] && smQ[# + 1] &]
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